Date of Award


Degree Type


Degree Name

Doctor of Philosophy



First Advisor

Katie E. Mosack

Committee Members

Raymond Fleming, Amy E. Harley, W. Hobart Davies, Shawn Cahill


Intervention, Motivation, Nutrition, Self-As-Doer, Self-Identity, Theory of Planned Behavior


Background: Self-identity predicts healthy eating behaviors and intentions above and beyond Theory of Planned Behavior components (TPB; i.e., attitudes, perceived behavioral control, and subjective norms), but interventions exploring the relationship between self-identity and motivation are limited. Self-as-doer identity may be an important point of intervention for healthy eating behaviors (Houser-Marko & Sheldon, 2006). Therefore, I investigated whether the experimental manipulation of a self-as-doer identity predicted improved healthy food consumption, intentions, and increased self-identity as a healthy eater compared to women who received nutritional education or no intervention directly following the intervention and one month post-intervention.

Method: Participants were 79 women ages 18-53 years old (M=22.92, SD=6.92) who were randomly assigned to one of three conditions (i.e., control, education only, or education and self-as-doer activity) and asked to record their diet for four days using a food diary and an online food frequency questionnaire. Intentions to eat a healthy diet, nutrition knowledge, identity as a healthy eater, and healthy eating behaviors were recorded over a six week period: before, after, and one month post-intervention. Repeated measures ANOVAs and hierarchal linear regressions were performed to determine if the self-as-doer intervention created change and predicted increases in intentions, self-identity, and healthy food consumption.

Results: Healthy eater identity predicted intentions to eat a healthy diet and overall healthy eating behavior above and beyond TPB components, but did not predict specific food group eating behaviors. Self-as-doer participants strengthened self-identity and intentions over the course of the study, but no group differences were found. Self-as-doer participants increased overall healthy eating behaviors while education and control participants decreased overall healthy eating behaviors. Self-as-doer participants ate significantly more healthy foods at time three than did education and control participants.

Discussion: Findings support the role of self-identity in predicting intentions and overall healthy eating behaviors and demonstrate a causal relationship between self-as-doer identity and change in healthy eating identity, intentions, and some behaviors. The self-as-doer intervention may provide individuals with the unique motivational tools needed for diet change. Further research refining the self-as-doer intervention, targeting other health behaviors, and employing the intervention in a clinical population is needed.